1. Field of the Invention
The invention relates to a method and apparatus for attaching a continuous tape in a sewing machine to a circular edge of tubular workpiece such as the waist portion of a swimsuit or a brief, and automatically cutting the tape when the front and rear ends of the tape are overlap by a certain amount after the front end makes a full turn around the circular edge.
2. Description of the Prior Art
As a method for automatically cutting off the continuous tape when the front and rear ends of the tape overlap by a certain amount after the front end of the tape makes a full turn, a method is known for setting the number of sewing stitches preliminarily depending on the size of the tape attaching portion of the tubular workpiece, counting the number of stitches from the start of sewing, and driving the cutter when the number reaches the set value to cut off the tape.
In a flat workpiece, as a method for attaching a tape, a method is known for starting the counting of the number of stitches when the rear end of the workpiece is detected by an end detecting sensor disposed before a presser foot of the sewing machine, and cutting off the tape by driving the cutter when reaching a predetermined number of stitches.
In the conventional method of attaching a tape to a tubular workpiece, since the start of counting of the number of stitches is based on the start of sewing, even a small difference in every stitch between the feed amount of the workpiece and tape is accumulated during the sewing operation, and considerable variations occur in the overlapping amount of the tape at the end of sewing between sewn products. To prevent defects due to shortages of tape length, it is necessary to set the number of stitches somewhat larger, which gives rise to increased costs and impaired comfort of wearing or appearance of the sewn products.
When sewing products differing in properties in the workpiece or tape, or size or type of the tape sewing portion of the workpiece, the setting of the number of stitches must be changed every time, which is very bothersome.
The method of cutting the tape when the number of stitches reaches a preset number by detecting the cloth end cannot be directly applied to an endless tubular workpiece.